An activist from Louisville, Kentucky, was charged with attempted murder on Monday after shooting at mayoral candidate Craig Greenberg in his campaign office, police said on Tuesday, according to NBC News.

Quintez Brown, 21, was also arrested on four counts of wanton endangerment in connection with the incident, the Louisville Metro Police Department said.

The department did not provide details on any possible motive, but said it is believed the suspect acted alone.

According to the Courier Journal, Brown is a well-known civil rights activist in Louisville who also previously served as a former intern and editorial columnist for the newspaper.

He had recently announced that he would be running for Metro Council in District 5, according to the Courier Journal.

The shooting on Monday unfolded at Greenberg's office at Butchertown Market shortly after 10:00 a.m., police said during a news conference.

Greenberg later recalled that the incident occurred as he was holding a meeting with members of his team.

The suspect, he said, walked into their office.

“When we greeted him, he pulled out a gun, aimed it directly at me and began shooting,” he added.

A bullet grazed his sweater but neither he nor campaign workers were injured. One campaign worker was able to shut the door and the suspect fled, according to Greenberg. He said the group then barricaded the room using desks and tables.